Surgery is performed under general anesthesia with the patient in the lateral decubitus position with the operated leg resting on a U-shaped pillow (Figure 12.3). A straight lateral incision approximately 20 cm in length is performed slightly anterior to the top of the greater trochanter (Figure 12.4). The subcutaneous tissue is dissected to expose the fascia lata and the gluteal fascia. The anterior border of the gluteus maximus is identified through transparency, and the fascia is divided along the anterior border of the gluteus maximus (Figure 12.5). Dissection is carried out to develop the interval between the gluteus maximus that is retracted posteriorly and the gluteus medius according to the Gibson approach⁴ (Figure 12.6). The Gibson approach is preferred to the classic Kocher-Langenbeck approach because the former does not violate the gluteus musculature and results in an improved cosmetic result. The fascia lata is opened toward the distal end of the incision. The trochanteric bursa is opened from posterior to anterior, exposing the greater trochanter and the insertion of the gluteus medius and origin of the vastus lateralis (Figure 12.7).

Although the original description by Ganz and colleagues¹ recommended that no attempt should be made to mobilize the gluteus medius or to visualize the piriformis tendon, we believe this step is important because it facilitates the correct level of the trochanteric osteotomy and reduces the bleeding at the time of capsular exposure. The gluteus medius insertion on the posterosuperior trochanter is identified and retracted anteriorly to facilitate exposure of the gluteus minimus and the piriformis tendon (Figure 12.8). The piriformis tendon is easily palpated and the fascia on top of it incised to expose the tendon. Internal rotation of the hip facilitates exposure of the piriformis. Careful dissection proximal to the piriformis tendon is recommended to avoid damage to the anastomosis between the inferior gluteal artery system and the deep branch of the medial circumflex artery that usually runs distal to the tendon. The fascia on top of the gluteus minimus tendon is incised after the piriformis tendon is pulled posteriorly. The gluteus minimus is then retracted anterior-superiorly exposing the hip capsule (Figure 12.9). Distally, the posterior fascia of the vastus lateralis is identified and incised longitudinally, leaving about a 3-mm cuff of fascia for later repair. The vastus lateralis is dissected from the femur anteriorly, and a Hohmann retractor is placed under the muscle, avoiding damage to the periosteum (Figure 12.10).

In preparation for the trochanteric osteotomy, an incision is made from the posterosuperior border of the greater trochanter extending distally to the posterior edge of the vastus lateralis (Figure 12.11). There are two ways to perform the trochanteric osteotomy:

The trochanteric piece is flipped and mobilized anteriorly with the attached vastus lateralis and gluteus medius. Posteriorly, the previously exposed gluteus minimus is
further completely elevated anteriorly off the hip capsule. The gluteus minimus should be released posteriorly as far as the level of the sciatic notch—this will avoid difficulty with acetabular exposure. Distally, the anterolateral portion of the vastus lateralis is released from the femur along with the insertion of the vastus intermedius, which is facilitated by flexion, abduction, and external rotation of the hip. The hip capsule is completely exposed from the anterior to the posterosuperior aspect (Figure 12.13). With complete exposure of the capsule, a capsulotomy is performed in a Z shape fashion (right hip) or reverse Z shape (left hip). The capsule is cut initially in line with the longitudinal axis of the anterior neck, starting at the superoanterior corner of the trochanteric osteotomy. The longitudinal flap is only partially opened. The distal capsulotomy extends anterior toward the anteroinferior aspect of the acetabulum. Finishing the distal anteroinferior flap allows for safe completion of the longitudinal flap to the level of the acetabular labrum. At the level of the labrum, the capsular opening is curved posteriorly parallel
to the acetabular rim and toward the piriformis tendon. With the capsule opened, the joint is inspected for signs of synovitis and for dynamic assessment of range of motion with special attention to flexion and internal rotation. Intra- and extra-articular causes of FAI can be dynamically determined (Figure 12.14). Flexion, adduction, and external rotation allow for subluxation of the hip. Further resection of the ligamentum teres allows a complete dislocation of the femoral head. Once the femoral head is dislocated from the acetabulum, the leg is placed in a sterile bag on the opposite side of the table (Figure 12.15).